/*
 * Created by 2006-7-3 下午09:12:52
 * $Id: RandomGUID.java 76 2006-07-06 17:03:18Z wjx $
 */
package com.someok.utils.codec;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.security.SecureRandom;
import java.util.Random;

/**
 * 
 * <p><a href="RandomGUID.java.html"><i>View Source</i></a></p>
 *
 * @author wjx
 * @version $Revision: 76 $ $Date: 2006-07-07 01:03:18 +0800 (星期五, 07 七月 2006) $
 */
public class RandomGUID {
    private static Random myRand;
    private static SecureRandom mySecureRand;
    private static String s_id;

    /*
     * Static block to take care of one time secureRandom seed.
     * It takes a few seconds to initialize SecureRandom.  You might
     * want to consider removing this static block or replacing
     * it with a "time since first loaded" seed to reduce this time.
     * This block will run only once per JVM instance.
     */
    static {
        mySecureRand = new SecureRandom();

        long secureInitializer = mySecureRand.nextLong();
        myRand = new Random(secureInitializer);

        try {
            s_id = InetAddress.getLocalHost().toString();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }

    public String valueBeforeMD5 = "";
    public String valueAfterMD5 = "";

    /**
     * Default constructor.  With no specification of security option,
     * this constructor defaults to lower security, high performance.
     */
    public RandomGUID() {
        getRandomGUID(false);
    }

    /**
     * Constructor with security option.  Setting secure true
     * enables each random number generated to be cryptographically
     * strong.  Secure false defaults to the standard Random function seeded
     * with a single cryptographically strong random number.
     */
    public RandomGUID(boolean secure) {
        getRandomGUID(secure);
    }

    /**
     * Method to generate the random GUID
     */
    private void getRandomGUID(boolean secure) {
        
        StringBuffer sbValueBeforeMD5 = new StringBuffer();

        
        try {
            long time = System.currentTimeMillis();
            long rand = 0;

            if (secure) {
                rand = mySecureRand.nextLong();
            } else {
                rand = myRand.nextLong();
            }

            // This StringBuffer can be a long as you need; the MD5
            // hash will always return 128 bits.  You can change
            // the seed to include anything you want here.
            // You could even stream a file through the MD5 making
            // the odds of guessing it at least as great as that
            // of guessing the contents of the file!
            sbValueBeforeMD5.append(s_id);
            sbValueBeforeMD5.append(":");
            sbValueBeforeMD5.append(Long.toString(time));
            sbValueBeforeMD5.append(":");
            sbValueBeforeMD5.append(Long.toString(rand));

            valueBeforeMD5 = sbValueBeforeMD5.toString();
            MD5 md5 = new MD5(valueBeforeMD5);

            byte[] array = md5.processString();
            StringBuffer sb = new StringBuffer();

            for (int j = 0; j < array.length; ++j) {
                int b = array[j] & 0xFF;

                if (b < 0x10) {
                    sb.append('0');
                }

                sb.append(Integer.toHexString(b));
            }

            valueAfterMD5 = sb.toString();
        } catch (Exception e) {
            System.out.println("Error:" + e);
        }
    }

    /**
     * Convert to the standard format for GUID
     * (Useful for SQL Server UniqueIdentifiers, etc.)
     * Example: C2FEEEAC-CFCD-11D1-8B05-00600806D9B6
     */
    public String toString() {
        String raw = valueAfterMD5.toUpperCase();
        StringBuffer sb = new StringBuffer();
        sb.append(raw.substring(0, 8));
        sb.append("-");
        sb.append(raw.substring(8, 12));
        sb.append("-");
        sb.append(raw.substring(12, 16));
        sb.append("-");
        sb.append(raw.substring(16, 20));
        sb.append("-");
        sb.append(raw.substring(20));

        return sb.toString();
    }

    /**
     * Demonstraton and self test of class
     */
    public static void main(String[] args) {
    	long b = System.currentTimeMillis();
        for (int i = 0; i < 1; i++) {
            RandomGUID myGUID = new RandomGUID();
            System.out.println("Seeding String=" + myGUID.valueBeforeMD5);
            System.out.println("rawGUID=" + myGUID.valueAfterMD5);
            System.out.println("RandomGUID=" + myGUID.toString());
            System.out.println("RandomGUID=" + new RandomGUID().toString());
            System.out.println("RandomGUID=" + new RandomGUID().toString());
            System.out.println("RandomGUID=" + new RandomGUID().toString());
            System.out.println("RandomGUID=" + new RandomGUID().toString());
			System.out.println("rawGUID=" + new RandomGUID().valueAfterMD5.toUpperCase());
			System.out.println("rawGUID=" + new RandomGUID().valueAfterMD5.toUpperCase());
			System.out.println("rawGUID=" + new RandomGUID().valueAfterMD5.toUpperCase());
			System.out.println("rawGUID=" + new RandomGUID().valueAfterMD5.toUpperCase());
        }
        System.out.println("Total Time : " + (System.currentTimeMillis() - b));
    }
}